Russian Deputy Prime Minister Yuri Borisov is furious about a story published by the newspaper Kommersant citing an unnamed source at Roscosmos who claims the Russian space agency now suspects American astronauts aboard the International Space Station of sabotaging a module last month, supposedly in order to expedite the return of an ailing colleague.

“It’s absolutely unacceptable to cast aspersions on either our cosmonauts or the American astronauts,” Borisov told reporters on Wednesday. “A commission is underway, and it is by no means possible to pass such verdicts until the investigation is complete. We must wait for the final results of this work, before understanding the nature of this hole. It’s entirely possible that it could have been caused by a manufacturing defect. You can invent as many scenarios as you like.”

Borisov stressed that the ISS crew responded to the discovery of the hole swiftly and professionally, telling journalists that outer space is no place for political disagreements. “Right now, before the investigation is done, throwing out labels and going on some witch hunt is, to put it mildly, short-sighted and dangerous.”

A day earlier, on September 11, Roscosmos general director Dmitry Rogozin noted that the situation surrounding the hole discovered on August 30 was more complicated than originally thought. On Wednesday, however, responding to the story in Kommersant, Rogozin wrote on Facebook: “Spreading guesswork and rumors about what happened aboard the ISS doesn’t help the work being done by Roscosmos experts and is aimed at undermining camaraderie among the space station’s crew. Before the Roscosmos special commission’s work is done, any claims based on ‘sources’ are unacceptable.”

On August 30, Houston and Moscow noticed a drop in pressure aboard the ISS. Crew members later discovered the hole and German astronaut Alexander Gerst was kind enough to cork it with his finger, while his colleagues rigged a less-flesh-based plug made of rubber and vacuum-proof sealant. Russia’s national space agency says it’s still investigating whether the hole was drilled deliberately or in error, on the ground or in orbit.